DONNER SUMMIT (CBS13) – A big rig accident at the Donner Summit stopped all eastbound traffic on Highway 80 for several hours on Thursday, according to the California Highway Patrol.

The accident happened at about 10:30 a.m. when two trailers ended up on their sides. Eastbound 80 was completely closed at Boreal Road for nearly five hours. As of 3:27 p.m., the left lane was still closed and traffic was moving slowing through the area in the right lane.

According to the CHP, an environmental health official from Nevada County was called out to check the contents of one of the trailers. It was reportedly carrying 5.5 gallons of nitrous oxide.

Motorists were being detoured to westbound 80, exiting at Soda Springs, then east on Donner Pass Road to the Donner Lake interchange and back to eastbound 80.

Trucks were not being allowed on that detour and were being turned around.